Investigation of dislocation networks in dispersion-strengthened aluminum

Dislocation networks in dispersion-strengthened aluminum produced by hot ex trusion were investigated by transmission electron microscopy. Owing to the close dislocation spacings, the weak-beam technique had to be employed. Bu rgers vectors and line directions were determined in the as-produced state and after annealing above the extrusion temperature. The dislocation networ ks show remarkable regularity and can be grouped into three different types according to their dislocation arrangement, spacings and Burgers vectors. One type of the dislocation networks containing 60 degrees dislocations dis appears during annealing and therefore is suggested to be responsible for t he different mechanical properties of the material before and after heat tr eatment. (C) 1999 Elsevier Science S.A. All rights reserved.